L5980 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L5980' PDF : 37 Pages View PDF
Application information
Equation 17
fP0 = 0,
fP1
=
--------------1--------------- ,
2π ⋅ R3 ⋅ C3
fP2
=
---------------------1----------------------
2
π
⋅
R4
⋅
-C-----4----⋅---C-----5--
C4 + C5
Figure 10. Type III compensation network
L5980
In Figure 11 the Bode diagram of the PWM and LC filter transfer function (GPW0 · GLC(f))
and the open loop gain (GLOOP(f) = GPW0 · GLC(f) · GTYPEIII(f)) are drawn.
Figure 11. Open loop gain: module bode diagram
The guidelines for positioning the poles and the zeroes and for calculating the component
values can be summarized as follow:
1. Choose a value for R1, usually between 1 kΩ and 5 kΩ.
2. Choose a gain (R4/R1) in order to have the required bandwidth (BW), that means:
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